Date:
Name:
Partners:
Purpose: To examine and distinguish between physical and chemical changes.
Hypothesis: Chemical change can be recognized if the following changes are observed:
(LIST FIVE CLUES - 1/2 mark each)
Physical changes include: (LIST THREE-1/2 mark each)
Table 1: Safety Precautions:
1. For each chemical and risk listed, give 1 precaution you should take.
Chemical(s) Used & Risk
Precautions
Potassium hydroxide is very
corrosive.
Ammonium chloride is toxic if
ingested.
Hydrochloric acid is very
corrosive. (use 1 different
precaution from KOH)
Silver nitrate is a strong oxidizing
agent.
Potassium thiocyanate is a skin,
eye and respiratory tract irritant.
Phenolphthalein is flammable.
Iron (III) chloride is a severe body
tissue irritant.
Procedure:
1. Wear Goggles at all times
2. Pick up a test tube, test tube rack and test tube brush and take these with you to each station.
3. At each station, follow the written instructions, and record your observations in Table 2.
4. Clean your test tube after each station. Do not turn on/off tap with T.T. under tap to avoid
splashing.
5. After you complete all 7 stations wash your hands at the front sink.
Lab Tips:
1. Follow the written instructions with regards to quantities carefully. More chemicals does not
equal better results.
2. Place the test tubes in the plastic T.T. racks while pouring.
3. Temperature changes may be small so keep an eye on them.
Observations: see table 2 on the back of this page.
Table 2: Evidence of chemical and physical change. (Absent Student Sheet)
__ K
8
__A
7
__T
14
__C
9
__
4K
___
4K
Starting substances
Part
Reactants
Physical
properties
Observations
after mixing etc.
Inference
physical?
chemical?
Evidence
(as many as
possible) (7A)
water
1
Food
colouring
Potassium
hydroxide
2
Food colouring
dissolved in the
water
Solid, white
pellets
Water with
phenolphthalein
3
Ammonium
chloride
Solid, white
powder
Water
Sodium
chloride (aq)
4
5
Silver nitrate
(aq)
Iron (III)
chloride
Potassium
thiocyanate
6
Hydrochloric
acid
Crushed
Tums
Sugar
7
water
transparent,
colourless,
liquid
Transparent,
orange,
liquid
Solid, white,
small crystals
transparent,
colourless,
liquid
An increase in
temperature was
felt and a pink
colour was seen
___
14T
A decrease in
temperature was
felt
Small particles of
solid appeared
__
7A
The solution
turned a very
dark red
Bubbles formed
and eventually
the Tums were
gone
The sugar
dissolved in the
water
Discussion / Conclusion: (Answer on lined paper using full and complete sentences)
1.
Which stations resulted in a physical change? Use 1 example from your lab to explain how
you were able to determine they were physical changes? (2 marks)
2.
Which stations resulted in chemical changes? Use 2 examples from your lab to explain how
you were able to determine they were chemical changes? (3 marks)
3.
List 2 physical changes that you observe at home. For each example give a reason.(2marks)
4.
List 2 chemical changes that you observe at home. For each example give a reason.(2 marks)
___
9C